HULL  
   Ken ClarkSon's convex hulls, Delaunay triangulations, alpha shapes calculator in C
   http://cm.bell-labs.com/netlib/voronoi/hull.html

Magic Software  
   Dave Eberley's Code Page: Includes lot of Code that you might need while writing a Computational Geometric Software
   http://www.magic-software.com/

Polygon Boolean operations on sets of polygons  
   GDSII viewer + Algorithms for 2d polygon boolean operations, C++ source code
   http://www.xs4all.nl/~kholwerd/bool.html

Computational Geometry Code  
   Jeff Erickson's links to freely available implementations of geometric algorithms and software.
   http://compgeom.cs.uiuc.edu/~jeffe/compgeom/code.html

Fast Industrial-Strength Triangulation  
   By Martin Held. Copes with polygons with holes and degeneracies/self-intersections; based on repeatedly clipping ears. Source code on request.
   http://www.cosy.sbg.ac.at/~held/projects/triang/triang.html

QMG project  
   Mesh generation in 2D and 3D on Unix and NT, and related software by Steven Vavasis.
   http://www.cs.cornell.edu/Info/People/vavasis/qmg-home.html

Delaunay Triangulation Code  
   J-D. Boissonnat et al.'s code for Delaunay meshing in 2 and 3 dimensions in C++.
   http://www-sop.inria.fr/prisme/logiciel/del-tree.html

Fast Robust Predicates for Computational Geometry  
   C code for orientation and incircle tests using adaptive-precision floating-point arithmetic
   http://www.cs.cmu.edu/~quake/robust.html

Stony Brook Algorithm Repository - Section on Computational Geometry  
   Summary of major CG problems and implementations of their solutions
   http://www.cs.sunysb.edu/~algorith/major_section/1.6.shtml

JeoEdit  
   Two Java applets for editing polygons and point sets for input to computational geometry software.
   http://cgm.cs.mcgill.ca/~godfried/jeoedit/

Gmsh  
   Gmsh is a three-dimensional finite element mesh generator, primarily Delaunay, with built-in pre- and post-processing facilities. Gmsh is freely available for Windows and most UNIX platforms.
   http://www.geuz.org/gmsh/

Reviver Homepage  
   A Free Surface Reconstructor which turns unorganised point clouds to surfaces. Variety of Output Formats. (Surface Reconstruction Software)
   http://www.ams.sunysb.edu/~piyush/reviver

GTS - The GNU Triangulated Surface Library  
   Open-source library for manipulating 3D triangular surface meshes. Delaunay triangulations, robust geometric predicates, robust boolean set operations on surfaces, surface refinement and coarsening, level-of-detail, k-d trees, volume and curvature, strip
   http://gts.sourceforge.net/

Edgebreaker 3D Compression for Triangle Meshes  
   Source code, explanations, file formats, and examples of the Edgebreaker compression and decompression techniques.
   http://www.gvu.gatech.edu/~jarek/edgebreaker/eb/

Knotplot  
   A program for exploring topological knots and knot-like objects in a 3-D rendered environment offering stills, animated knots (including dynamic forces) and demos. Aimed at mathematician and artist alike.
   http://www.cs.ubc.ca/nest/imager/contributions/scharein/KnotPlot.html

Surface Evolver  
   Free interactive program for modelling liquid surfaces shaped by various forces and constraints, e.g., minimal surfaces (bubbles). Applies gradient descent to minimize energy. Available for most platforms.
   http://www.susqu.edu/facstaff/b/brakke/evolver/

Triangle  
   Jonathan Richard Shewchuk's Two-Dimensional Quality Mesh Generator and Delaunay Triangulator.
   http://www.cs.cmu.edu/~quake/triangle.html

CM2 Mesh Tools  
   Professional C++ mesh generators. Includes product information and news releases.
   http://www.computing-objects.com/en/meshtools.html

Knotenpunkt  
   Produces commercial software that creates a surface model out of a pointcloud or polymesh [Balingen, Germany].
   http://www.knotenpunkt.com/home_E.htm

Smallest Enclosing Ball of Points  
   Fast and robust C++ code available under GNU license. Handles arbitrary dimensions, and has high numerical stability.
   http://www.inf.ethz.ch/personal/gaertner/miniball.html

Polymake  
   A tool for the algorithmic treatment of polytopes and polyhedra.
   http://www.math.tu-berlin.de/polymake/

Amenta's Directory of Computational Geometry Software  
   Lot of categories and links.
   http://www.geom.uiuc.edu/software/cglist/

CGAL - Computational Geometry Algorithms Library  
   A collaborative effort to develop a robust, easy to use, and efficient C++ software library of geometric data structures and algorithms.
   http://www.cgal.org/

Mg R-tree Library  
   A simple C++ R-tree implementation with Segment Incidences Detector as an application.
   http://www.volny.cz/r-tree/

Qhull  
   Computes convex hulls, Delaunay triangulations, Voronoi diagrams, half-space intersections about a point, furthest-site Delaunay triangulations, and furthest-site Voronoi diagrams. It runs in 2-d, 3-d, 4-d, and higher dimensions.
   http://www.qhull.org/

Surface Reconstruction Algorithms Page  
   Links to Surface Reconstruction software, papers, people.
   http://www.compgeom.com/www.sites.html

atlas - differential geometry Maple package  
   Calculations in terms of manifolds, mappings, embeddings, submersions, p-forms, tensor fields etc. All calculations are as coordinate free as possible. Some calculations with non-numerical dimension are available. Modern differential geometry notations.
   http://www.graphtree.com/Maple/atlas/index.htm

FastGEO Computational Geometry Library  
   FastGEO, A computational geometry library written in the object pascal language.
   http://www.partow.net/projects/fastgeo/index.html